1. Field of the Invention
The present invention relates to a driving force transmitting device which is disposed in various kinds of appliances typified by such an apparatus for processing picture image information as: a copying machine for printing and outputting picture image information obtained by scanning a picture image of an original document; a printer for printing and outputting picture image information sent from a partner; a facsimile machine for sending picture image information obtained by scanning a picture image of an original document; and a scanner for capturing picture image information by scanning a picture image of an original document. In specific, the invention relates to a coupling structure of driving force transmitting members such as a gear member and a pulley member for transmitting a driving force.
2. Description of the Related Art
With regard to such an apparatus for processing picture image information as a copying machine for printing and outputting picture image information obtained by scanning a picture image of an original document, a printer for printing and outputting picture image information sent from a printer, a facsimile machine for sending picture image information obtained by scanning a picture image of an original document, and a scanner for capturing picture image information by scanning a picture image of an original document, new models have been developed one after another in order to provide an apparatus which is easy to handle for the user, endowed with a more convenient function, and more inexpensive.
In such a situation, a driving force transmitting mechanism which transmits a force for driving various kinds of appliances and members which are incorporated in an apparatus for processing picture image information, from a power source to the appliances and members, was developed and has been improved in accordance with the development of new models, accompanying which various kinds of driving force transmitting parts for transmitting a driving force by rotating have been manufactured. These driving force transmitting parts are classified into one which is formed by a piece of driving force transmitting member such as a gear member having one gear portion and a pulley member having one pulley portion, and one which is formed into one piece by selectively combining a plurality of gear portions and pulley portions. Hereafter, the part formed into one piece by selectively combining gear portions, pulley portions and the like will be referred to as a complex-type driving force transmitting part.
However, since a lot of driving force transmitting parts are used in an apparatus for processing picture image information, there exist a lot of driving force transmitting parts which are similar to each other, and in driving force transmitting parts which are newly manufactured as new models are developed, there exist a lot of driving force transmitting parts which are similar to driving force transmitting parts which have been adopted in existing models. A driving force transmitting part having a gear portion will be taken as an example to explain the variety of the driving force transmitting parts. Main factors for classifying the driving force transmitting parts are the number of teeth, a module, the width of a tooth, and a material. On the basis of these main factors, the driving force transmitting parts are placed at a suitable position in a driving force transmitting device. Moreover, other than these main factors, various factors such as the diameter of an axis, the number of ribs, and the shape of the rib exist as ones which are related to the variety of the driving force transmitting parts.
In an apparatus for processing picture image information, the more kinds of driving force transmitting parts are used, the more kinds of molds for molding the driving force transmitting parts are needed because the driving force transmitting parts except some special ones are generally molded by a resin in a mold, with the result that the productivity of the apparatus for processing picture image information is worsened and the manufacturing cost is affected and increased. As opposed to this, such an idea can be conceived that in the course of developing an apparatus for processing picture image information, the same kind of driving force transmitting parts are used where possible so as to be capable of using the driving force transmitting parts in common even in different models including the existing models, whereby the variety of the driving force transmitting parts is reduced to cut off the cost for molds, and the manufacturing cost of the apparatus for processing picture image information and the price of the apparatus for processing picture image information are prevented from rising.
As mentioned above, however, in the driving force transmitting parts, there exist complex-type driving force transmitting parts 1a, 1b, 1c as shown in FIGS. 86A-86C. These complex-type driving force transmitting parts 1a, 1b, 1c, in which two gear portions 2a, 2b; 2c, 2d; 2e, 2f having the same axial line and adjacent to each other in the axial line direction are formed into one piece, respectively, are constructed so as to transmit a driving force through between the gear portions 2a, 2b, between the gear portions 2c, 2d, and between the gear portions 2e, 2f. Not only the part made by forming two gear portions into one piece, but also a part made by forming a gear portion and a pulley portion into one piece and a part made by forming two pulley portions into one piece are included in the complex-type driving force transmitting parts.
Although such a complex-type driving force transmitting part is necessary for design of a driving force transmitting mechanism of an apparatus for processing picture image information, it can be used in common at very few positions as compared with the driving force transmitting part which is formed by a single piece without combining driving force transmitting members, and it is difficult to use it in common. Moreover, since the complex-type driving force transmitting part has a complicated shape as compared with the driving force transmitting part formed by a single piece without combining driving force transmitting members, the cost for molds is expensive. Furthermore, an idea to reduce the variety of these complex-type driving force transmitting parts is difficult to realize, and hence such an idea has not been conceived currently.
Apart from such a problem, Japanese Unexamined Patent Publication JP-A 4-246025 (1992) discloses a structure that one gear member and two pulley members serving as a plurality of driving force transmitting members which are rotatable about the same axial line and formed into different pieces, are coupled so as to transmit a driving force by rotating. The respective pulley members and the gear member are placed in a manner that the gear member is sandwiched by the pulley members, and are constructed so that a rotation force of the gear member can be transmitted to the respective pulley members which are adjacent to each other in the axial line direction of the gear, by engaging projections formed on the respective pulley members with nails formed on the gear member within through holes formed on the respective pulley members.
Based on such a technique as disclosed by JP-A 4-246025, as shown in FIGS. 87A-87C, it can be considered to couple a gear member 4a having convex coupling portions 3a and a gear member 4b having concave coupling portions 3b by making the convex coupling portions 3a to be fitted into the concave coupling portions 3b so as to rotate and transmit a driving force, thereby fabricating a complex-type driving force transmitting part 5. According to this idea, however, there are two problems as described below.
Firstly, in the case of using the same kind of driving force transmitting members, i.e., gear members, when gear members having the same main factors as mentioned above are combined to form a complex-type driving force transmitting part, two patterns of gear members including a gear member having a convex coupling portion and a gear member having a concave coupling portion are required in spite of using one kind of gear members. Secondly, when plural kinds of gear members are combined to form a complex-type driving force transmitting part, in order to enable to fabricate all kinds of complex-type driving force transmitting parts which can be combined, it is necessary to prepare two patterns of gear members for each kind, as well as when the same kind of gear members are assembled.
These problems are opposed to questing commonality of driving force transmitting parts and reducing the number of molds, and the technique as shown in FIGS. 87A-87C cannot accomplish the above-said object of enhancing the productivity of an apparatus for processing picture image information and reducing the manufacturing cost.